Bladed spokes and tensiometer?



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A

Alan

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How would you verify the tension of a wheel built with bladed spokes such as Sapim CX-Rays? Would
the tensiometer readings still be valid?

alan
 
Q

Qui Si Parla Ca

Guest
Alan-<< How would you verify the tension of a wheel built with bladed spokes such as Sapim CX-Rays?
Would the tensiometer readings still be valid?

It is for the new DT tensionometer...

Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
(303)440-3535 http://www.vecchios.com "Ruote convenzionali costruite eccezionalmente bene"
 
A

Alan

Guest
> It is for the new DT tensionometer...
>
No, for the standard Wheelsmith one. Just not sure if the deflection measurement is accurate and
reliable if I were to use it.

alan
 
N

Nick Payne

Guest
On mine there is no conversion table for that size of spoke. Even when the spokes are bar tight the
deflection readings are still very small (10-15). I just used the table column for 0.9x3.1 spokes
and a fudge factor to account for the spokes only being 0.9x2.3 cross section.

Nick

"Alan" <[email protected]> wrote in message news:[email protected]...
> >
> > It is for the new DT tensionometer...
> >
> No, for the standard Wheelsmith one. Just not sure if the deflection measurement is accurate and
> reliable if I were to use it.
>
> alan
 
J

Jobst Brandt

Guest
Nick Payne writes:

>>>> How would you verify the tension of a wheel built with bladed spokes such as Sapim CX-Rays?
>>>> Would the tensiometer readings still be valid?

>>> It is for the new DT tensionometer...

>> No, for the standard Wheelsmith one. Just not sure if the deflection measurement is accurate and
>> reliable if I were to use
>> it.

> On mine there is no conversion table for that size of spoke. Even when the spokes are bar tight
> the deflection readings are still very small (10-15). I just used the table column for 0.9x3.1
> spokes and a fudge factor to account for the spokes only being 0.9x2.3 cross section.

These instruments all measure across the spoke thickness so the thickness enters into the reading.
For this reason I built my own instrument that was in small production for a year or so, first under
Avocet, and then under DT. In all about 120 reached the market. Unfortunately, all such instruments
are designed by people unclear on the problem.

The bending stiffness of the spoke also enters into the measurement that is based on the theory that
the spoke is a flexible strand although it is not entirely so. For that reason a small test load
that causes little bending must be used, but this in turn requires a precise measuring instrument.
For that purpose I used a 0.0001 resolution dial gauge.

In addition, small irregularities in spokes are large enough to distort readings and for this
purpose my instrument had a "tare" zero adjustment that was set in situ. Currently the tensiometer
problem is not served as well as it could be.

Jobst Brandt [email protected] Palo Alto CA
 
A

Alan

Guest
> adjustment that was set in situ. Currently the tensiometer problem is not served as well as it
> could be.
>
So what to do for bladed spokes?? Best guess?

alan
 
J

Jobst Brandt

Guest
Alan who? writes:

>> adjustment that was set in situ. Currently the tensiometer problem is not served as well as it
>> could be.

> So what to do for bladed spokes?? Best guess?

I use my tensiometer that is accurate for spokes of any thickness less than 2.5mm diameter, a number
I think approaches the stiff bar of steel size.

Jobst Brandt [email protected] Palo Alto CA
 
A

Alan

Guest
> I use my tensiometer that is accurate for spokes of any thickness less than 2.5mm diameter, a
> number I think approaches the stiff bar of steel size.
>
I may be confused but aren't all spokes pretty much less than 2.5mm, all of DT's spokes are.

Alan "confused" Wu
 
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